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Date: Tue, 30 Jun 2009 19:40:02 GMT
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To: freebsd-net@FreeBSD.org
From: Mikolaj Golub <to.my.trociny@gmail.com>
Cc: 
Subject: Re: kern/134557: [netgraph] [hang] 7.2 with mpd5.3 hanging up -
	ng_pptp problem
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The following reply was made to PR kern/134557; it has been noted by GNATS.

From: Mikolaj Golub <to.my.trociny@gmail.com>
To: bug-followup@FreeBSD.org
Cc: freebsd-net@FreeBSD.org, Sergei Cherveni <sergei.cherveni@gmail.com>, Alexander Motin <mav@FreeBSD.org>
Subject: Re: kern/134557: [netgraph] [hang] 7.2 with mpd5.3 hanging up - ng_pptp problem
Date: Tue, 30 Jun 2009 22:33:12 +0300

 --=-=-=
 
 Unfortunately, the problem was introduced by this commit :-)
 
 ----------
 
 Author: 	mav
 Date: 	Sat Jan 31 12:48:09 2009 UTC (4 months, 4 weeks ago)
 Log Message: 	
 
 MFC rev. 187495
 
 Check for infinite recursion possible on some broken PPTP/L2TP/... VPN setups.
 Mark packets with mbuf_tag on first interface passage and drop on second.
 
 PR:		ports/129625, ports/125303
 
 ----------
 
 If a packet goes through two or more ng interfaces, "while" loop in the tag
 checking code can run infinitely. The attached patch should fix this.
 
 -- 
 Mikolaj Golub
 
 
 --=-=-=
 Content-Type: text/x-diff
 Content-Disposition: attachment; filename=ng_iface.c.patch
 
 --- netgraph/ng_iface.c.orig	2009-06-30 21:47:54.000000000 +0300
 +++ netgraph/ng_iface.c	2009-06-30 21:49:29.000000000 +0300
 @@ -365,7 +365,8 @@
  	}
  
  	/* Protect from deadly infinite recursion. */
 -	while ((mtag = m_tag_locate(m, MTAG_NGIF, MTAG_NGIF_CALLED, NULL))) {
 +	mtag = NULL;
 +	while ((mtag = m_tag_locate(m, MTAG_NGIF, MTAG_NGIF_CALLED, mtag))) {
  		if (*(struct ifnet **)(mtag + 1) == ifp) {
  			log(LOG_NOTICE, "Loop detected on %s\n", ifp->if_xname);
  			m_freem(m);
 
 --=-=-=--